Codebook subset restriction for enhanced type II channel state information reporting

ABSTRACT

A base station may transmit to a device an indication of codebook subset restriction (CBSR), which includes at least a restriction on a frequency basis. The device may receive the indication of CBSR, and may transmit to the base station channel state information (CSI) according to the received indication of CBSR. The indication of CBSR may also include a restriction on a spatial basis and restrict the device from reporting the CSI based on a subset of the frequency basis in addition to the spatial basis per configuration of the base station. The indication of CBSR may include a separately configured maximum allowed amplitude of a weighting coefficient for the spatial basis and the frequency basis, where the weighting coefficient is associated with a column vector of a precoding matrix used by the base station and the device. The number of frequency bases and the frequency compression units may be determined based on a number of different criteria, for example the number of antennas, the number of subbands, etc.

PRIORITY CLAIM

This application is a continuation of U.S. patent application Ser. No.16/735,750 titled “Codebook Subset Restriction for Enhanced Type IIChannel State Information Reporting”, filed on Jan. 7, 2020, whichitself claims benefit of priority of Chinese Patent Application Serialno. 201910018336.3 titled “Codebook Subset Restriction for Enhanced TypeII Channel State Information Reporting”, filed on Jan. 9, 2019, both ofwhich are hereby incorporated by reference as though fully andcompletely set forth herein.

The claims in the instant application are different than those of theparent application or other related applications. The Applicanttherefore rescinds any disclaimer of claim scope made in the parentapplication or any predecessor application in relation to the instantapplication. The Examiner is therefore advised that any such previousdisclaimer and the cited references that it was made to avoid, may needto be revisited. Further, any disclaimer made in the instant applicationshould not be read into or against the parent application or otherrelated applications.

FIELD OF THE INVENTION

The present application relates to wireless communications, and moreparticularly to channel state information reporting during wirelesscellular communications, e.g. during 5G-NR communications.

DESCRIPTION OF THE RELATED ART

Wireless communication systems are rapidly growing in usage. In recentyears, wireless devices such as smart phones and tablet computers havebecome increasingly sophisticated. In addition to supporting telephonecalls, many mobile devices (i.e., user equipment devices or UEs) nowprovide access to the internet, email, text messaging, and navigationusing the global positioning system (GPS), and are capable of operatingsophisticated applications that utilize these functionalities.Additionally, there exist numerous different wireless communicationtechnologies and standards. Some examples of wireless communicationstandards include GSM, UMTS (WCDMA, TDS-CDMA), LTE, LTE Advanced(LTE-A), HSPA, 3GPP2 CDMA2000 (e.g., 1×RTT, 1×EV-DO, HRPD, eHRPD), IEEE802.11 (WLAN or Wi-Fi), IEEE 802.16 (WiMAX), BLUETOOTH™, etc. A nexttelecommunications standards moving beyond the current InternationalMobile Telecommunications-Advanced (IMT-Advanced) Standards is called5th generation mobile networks or 5th generation wireless systems,referred to as 3GPP NR (otherwise known as 5G-NR for 5G New Radio, alsosimply referred to as NR). NR proposes a higher capacity for a higherdensity of mobile broadband users, also supporting device-to-device,ultra-reliable, and massive machine communications, as well as lowerlatency and lower battery consumption, than current LTE standards.

In general, wireless communication technologies, such as cellularcommunication technologies, are substantially designed to provide mobilecommunication capabilities to wireless devices. The ever increasingnumber of features and functionality introduced in wirelesscommunication devices creates a continuous need for improvement in bothwireless communications and in wireless communication devices. Inparticular, it is important to ensure the accuracy of transmitted andreceived signals. The UEs, which may be mobile telephones or smartphones, portable gaming devices, communication systems/devices housed inor otherwise carried by transportation vehicles (e.g. cars, buses,trains, trucks, motorcycles, etc.), laptops, wearable devices, PDAs,tablets, portable Internet devices, music players, data storage devices,or other handheld devices, etc. are generally powered by a portablepower supply, e.g., a battery and may have multiple radio interfacesthat enable support of multiple radio access technologies (RATs) asdefined by the various wireless communication standards (LTE, LTE-A,5G-NR, Wi-Fi, BLUETOOTH™, etc.). There are ongoing efforts to achieveefficient use of wireless communication resources and thereby increasesystem and device operation efficiency.

Many wireless communication standards provide for the use of knownsignals (e.g., pilot or reference signals) for a variety of purposes,such as synchronization, measurements, equalization, control, etc. Forexample, in cellular wireless communications, reference signals (RS, forshort) represent a special signal that exists only at the physical layerand is not used for delivering any specific information but to deliver areference point for the downlink power. When a wireless communicationdevice or mobile device (UE) attempts to determine downlink power (e.g.the power of the signal from a base station, such as eNB for LTE and gNBfor NR), it measures the power of the reference signal and uses it todetermine the downlink cell power. The reference signal also assists thereceiver in demodulating the received signals. Since the referencesignals include data known to both the transmitter and the receiver, thereceiver may use the reference signal to determine/identify variouscharacteristics of the communication channel. This is commonly referredto as ‘Channel Estimation’, which is a critical part of many high-endwireless communications such as LTE and 5G-NR communications. Knownchannel properties of a communication link in wireless communicationsare referred to as channel state information (CSI), which providesinformation indicative of the combined effects of, for example,scattering, fading, and power decay with distance. The CSI makes itpossible to adapt transmissions to current channel conditions, which iscrucial for achieving reliable communications with high data rates inmulti-antenna systems.

Oftentimes multi-antenna systems use precoding for improvedcommunications. Precoding is an extension of beamforming to supportmulti-stream (or multi-layer) transmissions for multi-antenna wirelesscommunications and is used to control the differences in signalproperties between the respective signals transmitted from multipleantennas by modifying the signal transmitted from each antenna accordingto a precoding matrix. In one sense, precoding may be considered aprocess of cross coupling the signals before transmission (in closedloop operation) to equalize the demodulated performance of the layers.The precoding matrix is generally selected from a codebook that definesmultiple precoding matrix candidates, and a precoding matrix candidateis typically selected according to a desired performance level, based onany of a number of different factors, such as current systemconfiguration, communication environment, and/or feedback informationfrom the receiver, e.g. a mobile device (UE) receiving the transmittedsignal(s).

The feedback information is used in selecting a precoding matrixcandidate by defining the same codebook at both the transmitter (whichmay be a base station) and the receiver (which may be a mobile device,or UE), and using the feedback information from the receiver as anindication of a preferred precoding matrix. In such cases the feedbackinformation includes what is referred to as a precoding matrix index(PMI), which can be based on properties of the signals received at thereceiver. For example, the receiver may determine that a received signalhas relatively low signal-to-noise ratio (SNR), and may accordinglytransmit a PMI that would replace a current precoding matrix with a newprecoding matrix to increase the signal-to-noise ratio (SNR).

Under certain circumstances, the set of precoding matrix candidates thatcan be selected from the codebook may need to be limited. For example,the network may prevent the receiver from selecting some precodingmatrix candidates while allowing it to select others. This is commonlyreferred to as codebook subset restriction, or CBSR for short. CBSR mayinclude the transmission of a CBSR bitmap from a transmitter (e.g. abase station) to a receiver (e.g. a UE). The CBSR bitmap typicallyincludes a bit corresponding to each precoding matrix in the codebook,with the value of each bit (e.g., “0” or “1”) indicating to the receiverwhether or not the receiver is restricted from considering acorresponding precoding matrix candidate as a preferred precodingcandidate to request from the base station. One disadvantage of CBSR isincreased signaling overhead. For example, in some systems, the CBSRbitmap might contain a high number (e.g. 64) of bits per channel,requiring a transmitting device to transmit a relatively large amount ofinformation to implement CBSR for all of its channels.

Other corresponding issues related to the prior art will become apparentto one skilled in the art after comparing such prior art with thedisclosed embodiments as described herein.

SUMMARY OF THE INVENTION

Embodiments are presented herein of, inter alia, of methods andprocedures for support in various devices, e.g. wireless communicationdevices, to use codebook subset restriction (CBSR) based on both spatialconsiderations and frequency considerations for enhanced channel stateinformation (CSI) reporting during wireless communications, e.g. during5G-NR communications. Embodiments are further presented herein forwireless communication systems containing wireless communication devices(UEs) and/or base stations and access points (APs) communicating witheach other within the wireless communication systems.

In some embodiments, a base station may transmit, to a device, anindication of codebook subset restriction (CBSR), with the indicationincluding at least a restriction on a frequency basis. The device mayreceive the indication of CBSR, and may transmit, to the base station,channel state information (CSI) according to the received indication ofCBSR. The indication of CBSR may further include a restriction on aspatial basis and may restrict the device from reporting the CSI basedon a subset of the frequency basis in addition to the spatial basis perconfiguration of the base station. The indication of CBSR may include aseparately configured maximum allowed amplitude of a weightingcoefficient for the spatial basis and the frequency basis, with theweighting coefficient corresponding to a column vector of a precodingmatrix used by the base station and the device. A maximum allowedamplitude of a weighting coefficient included in the indication of CBSRmay be layer specific, and the weighting coefficient may be used indetermining a column vector of a precoding matrix used by the basestation and the device. In some embodiments, the indication of CBSRincludes a restricted spatial basis dependent amplitude of a weightingcoefficient and an unrestricted frequency basis dependent amplitude ofthe weighting coefficient, with the weighting coefficient associatedwith a column vector of a precoding matrix used by the base station andthe device.

The indication of CBSR may include a restricted frequency basisdependent amplitude of a weighting coefficient and an unrestrictedspatial basis dependent amplitude of the weighting coefficient, with theweighting coefficient associated with a column vector of a precodingmatrix used by the base station and the device. The indication of CBSRmay include a restricted frequency basis dependent amplitude of aweighting coefficient and a restricted spatial basis dependent amplitudeof the weighting coefficient, with the weighting coefficient associatedwith a column vector of a precoding matrix used by the base station andthe device. In some embodiments, the CBSR includes a maximum allowedamplitude of a weighting coefficient defined by a spatial basisdependent amplitude, a frequency basis dependent amplitude, and aspatial basis and frequency basis dependent amplitude, with theweighting coefficient associated with a column vector of a precodingmatrix used by the base station and the device. The indication of CBSRmay include a respective amplitude restriction corresponding to eachfrequency component, where the respective amplitude restriction is for aweighting coefficient associated with a column vector of a precodingmatrix used by the base station and the device.

The indication of CBSR may restrict the device from reporting a subsetof combinations of spatial and frequency basis per configuration of thebase station. The indication of CBSR may also configure a subset ofspatial basis groups and a respective set of frequency basis restrictionfor each of the spatial basis groups in the device. The CBSR may includea respective maximum allowed amplitude of a weighting coefficient foreach of the combinations of spatial and frequency basis, where theweighting coefficient is associated with a column vector of a precodingmatrix used by the base station and the device.

In some embodiments, an apparatus may operate to cause a device toobtain a value M for a spatial basis of an enhanced channel stateinformation (CSI) feedback, with the enhanced CSI feedback includinginformation for one or more spatial beams for a number of subbandsassociated with the enhanced CSI feedback. A coefficient of the spatialbasis may be based on M corresponding frequency bases, with the value Mdetermined in part based on the number of subbands, with M being lessthan the number of subbands. The device may transmit, to a base station,the enhanced CSI feedback based in part on the value M. In someembodiments, M may be selected by the device, which may transmit thevalue M in the enhanced CSI feedback. In some embodiments, the devicemay obtain the value M explicitly from the base station via dedicatedhigher-layer signaling. In such cases the value M is explicitlyconfigured in the device by the base station via higher-layer (e.g. RRC)signaling. Alternately, the value M may be derived by the device fromother parameters based on higher-layer signaling from the base stationand further based on specified, predefined rules. The value M may bedetermined in part based on one or more of a number N₁ of transmittingantennas in the vertical dimension, or a number N₂ of transmittingantennas in the horizontal dimension, with the one or more spatial beamsincluding multiple spatial beams divided into groups, with each grouphaving N₁×N₂ spatial bases.

The device may obtain a respective value M_(i) for each spatial basis ofa number of spatial bases of the enhanced channel CSI feedback, where acoefficient of each spatial basis is based on M_(i) correspondingfrequency bases, and each respective value M_(i) is determined in partbased on the number of subbands and is less than the number of subbands.In some embodiments, at least two of the M_(i) values differ from eachother. The device may transmit, to a base station, the enhanced CSIfeedback based in part on the respective M_(i) values.

This Summary is intended to provide a brief overview of some of thesubject matter described in this document. Accordingly, it will beappreciated that the above-described features are merely examples andshould not be construed to narrow the scope or spirit of the subjectmatter described herein in any way. Other features, aspects, andadvantages of the subject matter described herein will become apparentfrom the following Detailed Description, Figures, and Claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates an exemplary (and simplified) wireless communicationsystem, according to some embodiments;

FIG. 2 illustrates an exemplary base station in communication with anexemplary wireless user equipment (UE) device, according to someembodiments;

FIG. 3 illustrates an exemplary block diagram of a UE, according to someembodiments;

FIG. 4 illustrates an exemplary block diagram of a base station,according to some embodiments;

FIG. 5 shows an exemplary simplified block diagram illustrative ofcellular communication circuitry, according to some embodiments;

FIG. 6 shows an exemplary diagram illustrating a precoding structureassociated with Type II CSI reporting, according to prior art;

FIG. 7 shows, an exemplary diagram illustrating the reporting structureused by the UE to report back to a base station, according to prior art;

FIG. 8 shows, an exemplary diagram illustrating CBSR associated withType II CSI reporting, according to prior art;

FIG. 9 shows an exemplary diagram illustrating improved CBSR associatedwith Type II CSI reporting, according to some embodiments;

FIG. 10 shows a diagram illustrating one example of separate spatialbasis and frequency basis restrictions for improved CBSR, according tosome embodiments;

FIG. 11 shows a diagram illustrating one example of jointspatial-frequency restriction for improved CBSR, according to someembodiments;

FIG. 12 shows a diagram of an exemplary precoder structure withfrequency compression for improved CBSR, according to some embodiments;

FIG. 13 shows a diagram illustrating an example of PMI frequencycompression unit configuration for improved CBSR, according to someembodiments; and

FIG. 14 shows a table of exemplary exponent values for determining thefrequency bases corresponding to all considered subbands for improvedCBSR, according to some embodiments.

While features described herein are susceptible to various modificationsand alternative forms, specific embodiments thereof are shown by way ofexample in the drawings and are herein described in detail. It should beunderstood, however, that the drawings and detailed description theretoare not intended to be limiting to the particular form disclosed, but onthe contrary, the intention is to cover all modifications, equivalentsand alternatives falling within the spirit and scope of the subjectmatter as defined by the appended claims.

DETAILED DESCRIPTION OF THE EMBODIMENTS Acronyms

Various acronyms are used throughout the present application.Definitions of the most prominently used acronyms that may appearthroughout the present application are provided below:

-   -   AMR: Adaptive Multi-Rate    -   AP: Access Point    -   APN: Access Point Name    -   APR: Applications Processor    -   AS: Access Stratum    -   BS: Base Station    -   BSR: Buffer Size Report    -   BSSID: Basic Service Set Identifier    -   CBRS: Citizens Broadband Radio Service    -   CBSD: Citizens Broadband Radio Service Device    -   CBSR: Codebook Subset Restriction    -   CCA: Clear Channel Assessment    -   CMR: Change Mode Request    -   CS: Circuit Switched    -   CSI: Channel State Information    -   DL: Downlink (from BS to UE)    -   DSDS: Dual SIM Dual Standby    -   DYN: Dynamic    -   EDCF: Enhanced Distributed Coordination Function    -   FDD: Frequency Division Duplexing    -   FO: First-Order state    -   FT: Frame Type    -   GAA: General Authorized Access    -   GPRS: General Packet Radio Service    -   GSM: Global System for Mobile Communication    -   GTP: GPRS Tunneling Protocol    -   IMS: Internet Protocol Multimedia Subsystem    -   IP: Internet Protocol    -   IR: Initialization and Refresh state    -   KPI: Key Performance Indicator    -   LAN: Local Area Network    -   LBT: Listen Before Talk    -   LQM: Link Quality Metric    -   LTE: Long Term Evolution    -   MIMO: Multiple-In Multiple-Out    -   MNO: Mobile Network Operator    -   MU: Multi-User    -   NAS: Non-Access Stratum    -   NB: Narrowband    -   OOS: Out of Sync    -   PAL: Priority Access Licensee    -   PDCP: Packet Data Convergence Protocol    -   PDN: Packet Data Network    -   PDU: Protocol Data Unit    -   PGW: PDN Gateway    -   PLMN: Public Land Mobile Network    -   PSD: Power Spectral Density    -   PSS: Primary Synchronization Signal    -   PT: Payload Type    -   QBSS: Quality of Service Enhanced Basic Service Set    -   QI: Quality Indicator    -   RAN: Radio Access Network    -   RAT: Radio Access Technology    -   RF: Radio Frequency    -   ROHC: Robust Header Compression    -   RRC: Radio Resource Control    -   RTP: Real-time Transport Protocol    -   RTT: Round Trip Time    -   RX: Reception/Receive    -   SAS: Spectrum Allocation Server    -   SI: System Information    -   SID: System Identification Number    -   SIM: Subscriber Identity Module    -   SGW: Serving Gateway    -   SMB: Small/Medium Business    -   SSS: Secondary Synchronization Signal    -   TBS: Transport Block Size    -   TCP: Transmission Control Protocol    -   TDD: Time Division Duplexing    -   TX: Transmission/Transmit    -   UE: User Equipment    -   UI: User Interface    -   UL: Uplink (from UE to BS)    -   UMTS: Universal Mobile Telecommunication System    -   USIM: UMTS Subscriber Identity Module    -   WB: Wideband    -   Wi-Fi: Wireless Local Area Network (WLAN) RAT based on the        Institute of Electrical and Electronics Engineers' (IEEE) 802.11        standards    -   WLAN: Wireless LAN

Terms

The following is a glossary of terms that may appear in the presentapplication:

Memory Medium—Any of various types of non-transitory memory devices orstorage devices. The term “memory medium” is intended to include aninstallation medium, e.g., a CD-ROM, floppy disks, or tape device; acomputer system memory or random access memory such as DRAM, DDR RAM,SRAM, EDO RAM, Rambus RAM, etc.; a non-volatile memory such as a Flash,magnetic media, e.g., a hard drive, or optical storage; registers, orother similar types of memory elements, etc. The memory medium maycomprise other types of memory as well or combinations thereof. Inaddition, the memory medium may be located in a first computer system inwhich the programs are executed, or may be located in a second differentcomputer system which connects to the first computer system over anetwork, such as the Internet. In the latter instance, the secondcomputer system may provide program instructions to the first computersystem for execution. The term “memory medium” may include two or morememory mediums which may reside in different locations, e.g., indifferent computer systems that are connected over a network. The memorymedium may store program instructions (e.g., embodied as computerprograms) that may be executed by one or more processors.

Carrier Medium—a memory medium as described above, as well as a physicaltransmission medium, such as a bus, network, and/or other physicaltransmission medium that conveys signals such as electrical,electromagnetic, or digital signals.

Programmable Hardware Element—includes various hardware devicescomprising multiple programmable function blocks connected via aprogrammable interconnect. Examples include FPGAs (Field ProgrammableGate Arrays), PLDs (Programmable Logic Devices), FPOAs (FieldProgrammable Object Arrays), and CPLDs (Complex PLDs). The programmablefunction blocks may range from fine grained (combinatorial logic or lookup tables) to coarse grained (arithmetic logic units or processorcores). A programmable hardware element may also be referred to as“reconfigurable logic”.

Computer System (or Computer)—any of various types of computing orprocessing systems, including a personal computer system (PC), mainframecomputer system, workstation, network appliance, Internet appliance,personal digital assistant (PDA), television system, grid computingsystem, or other device or combinations of devices. In general, the term“computer system” may be broadly defined to encompass any device (orcombination of devices) having at least one processor that executesinstructions from a memory medium.

User Equipment (UE) (or “UE Device”)—any of various types of computersystems devices which perform wireless communications. Also referred toas wireless communication devices, many of which may be mobile and/orportable. Examples of UE devices include mobile telephones or smartphones (e.g., iPhone™, Android™-based phones) and tablet computers suchas iPad™, Samsung Galaxy™, etc., gaming devices (e.g. Sony PlayStation™, Microsoft XBox™, etc.), portable gaming devices (e.g.,Nintendo DS™, PlayStation Portable™, Gameboy Advance™, iPod™), laptops,wearable devices (e.g. Apple Watch™, Google Glass™), PDAs, portableInternet devices, music players, data storage devices, or other handhelddevices, etc. Various other types of devices would fall into thiscategory if they include Wi-Fi or both cellular and Wi-Fi communicationcapabilities and/or other wireless communication capabilities, forexample over short-range radio access technologies (SRATs) such asBLUETOOTH™, etc. In general, the term “UE” or “UE device” may be broadlydefined to encompass any electronic, computing, and/ortelecommunications device (or combination of devices) which is capableof wireless communication and may also be portable/mobile.

Wireless Device (or wireless communication device)—any of various typesof computer systems devices which performs wireless communications usingWLAN communications, SRAT communications, Wi-Fi communications and thelike. As used herein, the term “wireless device” may refer to a UEdevice, as defined above, or to a stationary device, such as astationary wireless client or a wireless base station. For example awireless device may be any type of wireless station of an 802.11 system,such as an access point (AP) or a client station (UE), or any type ofwireless station of a cellular communication system communicatingaccording to a cellular radio access technology (e.g. LTE, CDMA, GSM),such as a base station or a cellular telephone, for example.

Communication Device—any of various types of computer systems or devicesthat perform communications, where the communications can be wired orwireless. A communication device can be portable (or mobile) or may bestationary or fixed at a certain location. A wireless device is anexample of a communication device. A UE is another example of acommunication device.

Base Station (BS)—The term “Base Station” has the full breadth of itsordinary meaning, and at least includes a wireless communication stationinstalled at a fixed location and used to communicate as part of awireless telephone system or radio system.

Processor—refers to various elements (e.g. circuits) or combinations ofelements that are capable of performing a function in a device, e.g. ina user equipment device or in a cellular network device. Processors mayinclude, for example: general purpose processors and associated memory,portions or circuits of individual processor cores, entire processorcores or processing circuit cores, processing circuit arrays orprocessor arrays, circuits such as ASICs (Application SpecificIntegrated Circuits), programmable hardware elements such as a fieldprogrammable gate array (FPGA), as well as any of various combinationsof the above.

Channel—a medium used to convey information from a sender (transmitter)to a receiver. It should be noted that since characteristics of the term“channel” may differ according to different wireless protocols, the term“channel” as used herein may be considered as being used in a mannerthat is consistent with the standard of the type of device withreference to which the term is used. In some standards, channel widthsmay be variable (e.g., depending on device capability, band conditions,etc.). For example, LTE may support scalable channel bandwidths from 1.4MHz to 20 MHz. In contrast, WLAN channels may be 22 MHz wide whileBluetooth channels may be 1 Mhz wide. Other protocols and standards mayinclude different definitions of channels. Furthermore, some standardsmay define and use multiple types of channels, e.g., different channelsfor uplink or downlink and/or different channels for different uses suchas data, control information, etc.

Band—The term “band” has the full breadth of its ordinary meaning, andat least includes a section of spectrum (e.g., radio frequency spectrum)in which channels are used or set aside for the same purpose.Furthermore, “frequency band” is used to denote any interval in thefrequency domain, delimited by a lower frequency and an upper frequency.The term may refer to a radio band or an interval of some otherspectrum. A radio communications signal may occupy a range offrequencies over which (or where) the signal is carried. Such afrequency range is also referred to as the bandwidth of the signal.Thus, bandwidth refers to the difference between the upper frequency andlower frequency in a continuous band of frequencies. A frequency bandmay represent one communication channel or it may be subdivided intomultiple communication channels. Allocation of radio frequency ranges todifferent uses is a major function of radio spectrum allocation.

Wi-Fi—The term “Wi-Fi” has the full breadth of its ordinary meaning, andat least includes a wireless communication network or RAT that isserviced by wireless LAN (WLAN) access points and which providesconnectivity through these access points to the Internet. Most modernWi-Fi networks (or WLAN networks) are based on IEEE 802.11 standards andare marketed under the name “Wi-Fi”. A Wi-Fi (WLAN) network is differentfrom a cellular network.

Automatically—refers to an action or operation performed by a computersystem (e.g., software executed by the computer system) or device (e.g.,circuitry, programmable hardware elements, ASICs, etc.), without userinput directly specifying or performing the action or operation. Thusthe term “automatically” is in contrast to an operation being manuallyperformed or specified by the user, where the user provides input todirectly perform the operation. An automatic procedure may be initiatedby input provided by the user, but the subsequent actions that areperformed “automatically” are not specified by the user, i.e., are notperformed “manually”, where the user specifies each action to perform.For example, a user filling out an electronic form by selecting eachfield and providing input specifying information (e.g., by typinginformation, selecting check boxes, radio selections, etc.) is fillingout the form manually, even though the computer system must update theform in response to the user actions. The form may be automaticallyfilled out by the computer system where the computer system (e.g.,software executing on the computer system) analyzes the fields of theform and fills in the form without any user input specifying the answersto the fields. As indicated above, the user may invoke the automaticfilling of the form, but is not involved in the actual filling of theform (e.g., the user is not manually specifying answers to fields butrather they are being automatically completed). The presentspecification provides various examples of operations beingautomatically performed in response to actions the user has taken.

Approximately—refers to a value that is almost correct or exact. Forexample, approximately may refer to a value that is within 1 to 10percent of the exact (or desired) value. It should be noted, however,that the actual threshold value (or tolerance) may be applicationdependent. For example, in some embodiments, “approximately” may meanwithin 0.1% of some specified or desired value, while in various otherembodiments, the threshold may be, for example, 2%, 3%, 5%, and soforth, as desired or as required by the particular application.

Concurrent—refers to parallel execution or performance, where tasks,processes, or programs are performed in an at least partiallyoverlapping manner. For example, concurrency may be implemented using“strong” or strict parallelism, where tasks are performed (at leastpartially) in parallel on respective computational elements, or using“weak parallelism”, where the tasks are performed in an interleavedmanner, e.g., by time multiplexing of execution threads.

Station (STA)—The term “station” herein refers to any device that hasthe capability of communicating wirelessly, e.g. by using the 802.11protocol. A station may be a laptop, a desktop PC, PDA, access point orWi-Fi phone or any type of device similar to a UE. An STA may be fixed,mobile, portable or wearable. Generally in wireless networkingterminology, a station (STA) broadly encompasses any device withwireless communication capabilities, and the terms station (STA),wireless client (UE) and node (BS) are therefore often usedinterchangeably.

Configured to—Various components may be described as “configured to”perform a task or tasks. In such contexts, “configured to” is a broadrecitation generally meaning “having structure that” performs the taskor tasks during operation. As such, the component can be configured toperform the task even when the component is not currently performingthat task (e.g., a set of electrical conductors may be configured toelectrically connect a module to another module, even when the twomodules are not connected). In some contexts, “configured to” may be abroad recitation of structure generally meaning “having circuitry that”performs the task or tasks during operation. As such, the component canbe configured to perform the task even when the component is notcurrently on. In general, the circuitry that forms the structurecorresponding to “configured to” may include hardware circuits.

Transmission Scheduling—Refers to the scheduling of transmissions, suchas wireless transmissions. In cellular radio communications, signal anddata transmissions may be organized according to designated time unitsof specific duration during which transmissions take place. For example,in LTE, transmissions are divided into radio frames, each radio framebeing of equal (time) duration (e.g. each radio frame may be 10 ms). Aradio frame in LTE may be further divided into ten subframes, eachsubframe being of equal duration, with the subframes designated as thesmallest (minimum) scheduling unit, or the designated time unit for atransmission. Similarly, a smallest (or minimum) scheduling unit for 5GNR (or NR, for short) transmissions is referred to as a slot.Accordingly, as used herein, the term “slot” is used to reference asmallest (or minimum) scheduling time unit for the wirelesscommunications being described for NR communications. However, as notedabove, in different communication protocols such a scheduling time unitmay be named differently, e.g. a “subframe” in LTE, etc.

Various components may be described as performing a task or tasks, forconvenience in the description. Such descriptions should be interpretedas including the phrase “configured to.” Reciting a component that isconfigured to perform one or more tasks is expressly intended not toinvoke 35 U.S.C. § 112, paragraph six, interpretation for thatcomponent.

FIGS. 1 and 2—Exemplary Communication Systems

FIG. 1 illustrates an exemplary (and simplified) wireless communicationsystem, according to some embodiments. It is noted that the system ofFIG. 1 is merely one example of a possible system, and embodiments maybe implemented in any of various systems, as desired.

As shown, the exemplary wireless communication system includes a basestations 102A through 102N, also collectively referred to as basestation(s) 102 or base station 102. As shown in FIG. 1, base station102A communicates over a transmission medium with one or more userdevices 106A, 106B, etc., through 106N. Each of the user devices may bereferred to herein as a “user equipment” (UE) or UE device. Thus, theuser devices 106A through 106N are referred to as UEs or UE devices, andare also collectively referred to of UE(s) 106 or UE 106. Various onesof the UE devices may use codebook subset restriction (CBSR) based onboth spatial and frequency considerations for enhanced channel stateinformation (CSI) reporting during wireless communications, e.g. during5G-NR communications, according to various embodiments disclosed herein.

The base station 102A may be a base transceiver station (BTS) or cellsite, and may include hardware that enables wireless communication withthe UEs 106A through 106N. The base station 102A may also be equipped tocommunicate with a network 100, e.g., a core network of a cellularservice provider, a telecommunication network such as a public switchedtelephone network (PSTN), and/or the Internet, neutral host or variousCBRS (Citizens Broadband Radio Service) deployments, among variouspossibilities. Thus, the base station 102A may facilitate communicationbetween the user devices and/or between the user devices and the network100. The communication area (or coverage area) of the base station maybe referred to as a “cell.” It should also be noted that “cell” may alsorefer to a logical identity for a given coverage area at a givenfrequency. In general, any independent cellular wireless coverage areamay be referred to as a “cell”. In such cases a base station may besituated at particular confluences of three cells. The base station, inthis uniform topology, may serve three 120 degree beam width areasreferenced as cells. Also, in case of carrier aggregation, small cells,relays, etc. may each represent a cell. Thus, in carrier aggregation inparticular, there may be primary cells and secondary cells which mayservice at least partially overlapping coverage areas but on differentrespective frequencies. For example, a base station may serve any numberof cells, and cells served by a base station may or may not becollocated (e.g. remote radio heads). As also used herein, from theperspective of UEs, a base station may sometimes be considered asrepresenting the network insofar as uplink and downlink communicationsof the UE are concerned. Thus, a UE communicating with one or more basestations in the network may also be interpreted as the UE communicatingwith the network, and may further also be considered at least a part ofthe UE communicating on the network or over the network.

The base station(s) 102 and the user devices may be configured tocommunicate over the transmission medium using any of various radioaccess technologies (RATs), also referred to as wireless communicationtechnologies, or telecommunication standards, such as GSM, UMTS (WCDMA),LTE, LTE-Advanced (LTE-A), LAA/LTE-U, 5G-NR (NR, for short), 3GPP2CDMA2000 (e.g., 1×RTT, 1×EV-DO, HRPD, eHRPD), Wi-Fi, WiMAX etc. Notethat if the base station 102A is implemented in the context of LTE, itmay alternately be referred to as an ‘eNodeB’ or ‘eNB’. Note that if thebase station 102A is implemented in the context of 5G NR, it mayalternately be referred to as ‘gNodeB’ or ‘gNB’. In some embodiments,the base station 102 may communicate with UEs that use codebook subsetrestriction based on both spatial and frequency considerations forenhanced channel state information reporting during wirelesscommunications, e.g. during 5G-NR communications, as described herein.Depending on a given application or specific considerations, forconvenience some of the various different RATs may be functionallygrouped according to an overall defining characteristic. For example,all cellular RATs may be collectively considered as representative of afirst (form/type of) RAT, while Wi-Fi communications may be consideredas representative of a second RAT. In other cases, individual cellularRATs may be considered individually as different RATs. For example, whendifferentiating between cellular communications and Wi-Ficommunications, “first RAT” may collectively refer to all cellular RATsunder consideration, while “second RAT” may refer to Wi-Fi. Similarly,when applicable, different forms of Wi-Fi communications (e.g. over 2.4GHz vs. over 5 GHz) may be considered as corresponding to differentRATs. Furthermore, cellular communications performed according to agiven RAT (e.g. LTE or NR) may be differentiated from each other on thebasis of the frequency spectrum in which those communications areconducted. For example, LTE or NR communications may be performed over aprimary licensed spectrum as well as over a secondary spectrum such asan unlicensed spectrum. Overall, the use of various terms andexpressions will always be clearly indicated with respect to and withinthe context of the various applications/embodiments under consideration.

As shown, the base station 102A may also be equipped to communicate witha network 100 (e.g., a core network of a cellular service provider, atelecommunication network such as a public switched telephone network(PSTN), and/or the Internet, among various possibilities). Thus, thebase station 102A may facilitate communication between the user devicesand/or between the user devices and the network 100. In particular, thecellular base station 102A may provide UEs 106 with varioustelecommunication capabilities, such as voice, SMS and/or data services.

Base station 102A and other similar base stations (such as base stations102B . . . 102N) operating according to the same or a different cellularcommunication standard may thus be provided as a network of cells, whichmay provide continuous or nearly continuous overlapping service to UEs106A-106N and similar devices over a geographic area via one or morecellular communication standards.

Thus, while base station 102A may act as a “serving cell” for UEs106A-106N as illustrated in FIG. 1, each UE 106 may also be capable ofreceiving signals from (and possibly within communication range of) oneor more other cells (which might be provided by base stations 102B-Nand/or any other base stations), which may be referred to as“neighboring cells”. Such cells may also be capable of facilitatingcommunication between user devices and/or between user devices and thenetwork 100. Such cells may include “macro” cells, “micro” cells, “pico”cells, and/or cells which provide any of various other granularities ofservice area size. For example, base stations 102A-B illustrated in FIG.1 might be macro cells, while base station 102N might be a micro cell.Other configurations are also possible.

In some embodiments, base station 102A may be a next generation basestation, e.g., a 5G New Radio (5G NR) base station, or “gNB”. In someembodiments, a gNB may be connected to a legacy evolved packet core(EPC) network and/or to a NR core (NRC) network. In addition, a gNB cellmay include one or more transmission and reception points (TRPs). Inaddition, a UE capable of operating according to 5G NR may be connectedto one or more TRPs within one or more gNBs.

As mentioned above, UE 106 may be capable of communicating usingmultiple wireless communication standards. For example, a UE 106 mightbe configured to communicate using any or all of a 3GPP cellularcommunication standard (such as LTE or NR) or a 3GPP2 cellularcommunication standard (such as a cellular communication standard in theCDMA2000 family of cellular communication standards). Base station 102Aand other similar base stations operating according to the same or adifferent cellular communication standard may thus be provided as one ormore networks of cells, which may provide continuous or nearlycontinuous overlapping service to UE 106 and similar devices over a widegeographic area via one or more cellular communication standards.

The UE 106 might also or alternatively be configured to communicateusing WLAN, BLUETOOTH™, BLUETOOTH™ Low-Energy, one or more globalnavigational satellite systems (GNSS, e.g., GPS or GLONASS), one and/ormore mobile television broadcasting standards (e.g., ATSC-M/H or DVB-H),etc. Other combinations of wireless communication standards (includingmore than two wireless communication standards) are also possible.Furthermore, the UE 106 may also communicate with Network 100, throughone or more base stations or through other devices, stations, or anyappliances not explicitly shown but considered to be part of Network100. UE 106 communicating with a network may therefore be interpreted asthe UE 106 communicating with one or more network nodes considered to bea part of the network and which may interact with the UE 106 to conductcommunications with the UE 106 and in some cases affect at least some ofthe communication parameters and/or use of communication resources ofthe UE 106.

Furthermore, as also illustrated in FIG. 1, at least some of the UEs,e.g. UEs 106D and 106E may represent vehicles communicating with eachother and with base station 102, e.g. via cellular communications suchas 3GPP LTE and/or 5G-NR communications, for example. In addition, UE106F may represent a pedestrian who is communicating and/or interactingwith the vehicles represented by UEs 106D and 106E in a similar manner.Further aspects of vehicles communicating in network exemplified in FIG.1 will be discussed below, for example in the context ofvehicle-to-everything (V2X) communication such as the communicationsspecified by 3GPP TS 22.185 V.14.3.0, among others.

FIG. 2 illustrates an exemplary user equipment 106 (e.g., one of thedevices 106A through 106N) in communication with the base station 102and an access point 112, according to some embodiments. The UE 106 maybe a device with both cellular communication capability and non-cellularcommunication capability (e.g., BLUETOOTH™, Wi-Fi, and so forth) such asa mobile phone, a hand-held device, a computer or a tablet, or virtuallyany type of wireless device. The UE 106 may include a processor that isconfigured to execute program instructions stored in memory. The UE 106may perform any of the method embodiments described herein by executingsuch stored instructions. Alternatively, or in addition, the UE 106 mayinclude a programmable hardware element such as an FPGA(field-programmable gate array) that is configured to perform any of themethod embodiments described herein, or any portion of any of the methodembodiments described herein. The UE 106 may be configured tocommunicate using any of multiple wireless communication protocols. Forexample, the UE 106 may be configured to communicate using two or moreof CDMA2000, LTE, LTE-A, NR, WLAN, or GNSS. Other combinations ofwireless communication standards are also possible.

The UE 106 may include one or more antennas for communicating using oneor more wireless communication protocols according to one or more RATstandards. In some embodiments, the UE 106 may share one or more partsof a receive chain and/or transmit chain between multiple wirelesscommunication standards. The shared radio may include a single antenna,or may include multiple antenFnas (e.g., for MIMO) for performingwireless communications. Alternatively, the UE 106 may include separatetransmit and/or receive chains (e.g., including separate antennas andother radio components) for each wireless communication protocol withwhich it is configured to communicate. As another alternative, the UE106 may include one or more radios which are shared between multiplewireless communication protocols, and one or more radios which are usedexclusively by a single wireless communication protocol. For example,the UE 106 may include a shared radio for communicating using either ofLTE or CDMA2000 1×RTT or NR, and separate radios for communicating usingeach of Wi-Fi and BLUETOOTH™. Other configurations are also possible.

FIG. 3—Exemplary UE

FIG. 3 illustrates a block diagram of an exemplary UE 106, according tosome embodiments. As shown, the UE 106 may include a system on chip(SOC) 300, which may include portions for various purposes. For example,as shown, the SOC 300 may include processor(s) 302 which may executeprogram instructions for the UE 106 and display circuitry 304 which mayperform graphics processing and provide display signals to the display360. The processor(s) 302 may also be coupled to memory management unit(MMU) 340, which may be configured to receive addresses from theprocessor(s) 302 and translate those addresses to locations in memory(e.g., memory 306, read only memory (ROM) 350, NAND flash memory 310)and/or to other circuits or devices, such as the display circuitry 304,radio circuitry 330, connector I/F 320, and/or display 360. The MMU 340may be configured to perform memory protection and page tabletranslation or set up. In some embodiments, the MMU 340 may be includedas a portion of the processor(s) 302.

As shown, the SOC 300 may be coupled to various other circuits of the UE106. For example, the UE 106 may include various types of memory (e.g.,including NAND flash 310), a connector interface 320 (e.g., for couplingto the computer system), the display 360, and wireless communicationcircuitry (e.g., for LTE, LTE-A, NR, CDMA2000, BLUETOOTH™, Wi-Fi, GPS,etc.). The UE device 106 may include at least one antenna (e.g. 335 a),and possibly multiple antennas (e.g. illustrated by antennas 335 a and335 b), for performing wireless communication with base stations and/orother devices. Antennas 335 a and 335 b are shown by way of example, andUE device 106 may include fewer or more antennas. Overall, the one ormore antennas are collectively referred to as antenna(s) 335. Forexample, the UE device 106 may use antenna(s) 335 to perform thewireless communication with the aid of radio circuitry 330. As notedabove, the UE may be configured to communicate wirelessly using multiplewireless communication standards in some embodiments.

As further described herein, the UE 106 (and/or base station 102) mayinclude hardware and software components for implementing methods for atleast UE 106 to use codebook subset restriction based on both spatialand frequency considerations for enhanced channel state informationreporting during wireless communications, e.g. during 5G-NRcommunications, as further detailed herein. The processor(s) 302 of theUE device 106 may be configured to implement part or all of the methodsdescribed herein, e.g., by executing program instructions stored on amemory medium (e.g., a non-transitory computer-readable memory medium).In other embodiments, processor(s) 302 may be configured as aprogrammable hardware element, such as an FPGA (Field Programmable GateArray), or as an ASIC (Application Specific Integrated Circuit).Furthermore, processor(s) 302 may be coupled to and/or may interoperatewith other components as shown in FIG. 3, to use codebook subsetrestriction (CBSR) based on both spatial and frequency considerationsfor enhanced channel state information (CSI) reporting during wirelesscommunications, e.g. during 5G-NR communications, according to variousembodiments disclosed herein. Processor(s) 302 may also implementvarious other applications and/or end-user applications running on UE106.

In some embodiments, radio circuitry 330 may include separatecontrollers dedicated to controlling communications for variousrespective RAT standards. For example, as shown in FIG. 3, radiocircuitry 330 may include a Wi-Fi controller 356, a cellular controller(e.g. LTE and/or NR controller) 352, and BLUETOOTH™ controller 354, andin at least some embodiments, one or more or all of these controllersmay be implemented as respective integrated circuits (ICs or chips, forshort) in communication with each other and with SOC 300 (and morespecifically with processor(s) 302). For example, Wi-Fi controller 356may communicate with cellular controller 352 over a cell-ISM link or WCIinterface, and/or BLUETOOTH™ controller 354 may communicate withcellular controller 352 over a cell-ISM link, etc. While three separatecontrollers are illustrated within radio circuitry 330, otherembodiments have fewer or more similar controllers for various differentRATs that may be implemented in UE device 106. For example, at least oneexemplary block diagram illustrative of some embodiments of cellularcontroller 352 is shown in FIG. 5 as further described below.

FIG. 4—Exemplary Base Station

FIG. 4 illustrates a block diagram of an exemplary base station 102,according to some embodiments. It is noted that the base station of FIG.4 is merely one example of a possible base station. As shown, the basestation 102 may include processor(s) 404 which may execute programinstructions for the base station 102. The processor(s) 404 may also becoupled to memory management unit (MMU) 440, which may be configured toreceive addresses from the processor(s) 404 and translate thoseaddresses to locations in memory (e.g., memory 460 and read only memory(ROM) 450) or to other circuits or devices.

The base station 102 may include at least one network port 470. Thenetwork port 470 may be configured to couple to a telephone network andprovide a plurality of devices, such as UE devices 106, access to thetelephone network as described above in FIGS. 1 and 2. The network port470 (or an additional network port) may also or alternatively beconfigured to couple to a cellular network, e.g., a core network of acellular service provider. The core network may provide mobility relatedservices and/or other services to a plurality of devices, such as UEdevices 106. In some cases, the network port 470 may couple to atelephone network via the core network, and/or the core network mayprovide a telephone network (e.g., among other UE devices serviced bythe cellular service provider).

The base station 102 may include at least one antenna 434, and possiblymultiple antennas. The at least one antenna 434 may be configured tooperate as a wireless transceiver and may be further configured tocommunicate with UE devices 106 via radio 430. The antenna 434communicates with the radio 430 via communication chain 432.Communication chain 432 may be a receive chain, a transmit chain orboth. The radio 430 may be designed to communicate via various wirelesstelecommunication standards, including, but not limited to, LTE, LTE-A,5G-NR (or NR for short), WCDMA, CDMA2000, etc. The processor(s) 404 ofthe base station 102 may be configured to implement part or all of themethods described herein, e.g., by executing program instructions storedon a memory medium (e.g., a non-transitory computer-readable memorymedium), for base station 102 to communicate with a UE device that mayuse codebook subset restriction based on both spatial and frequencyconsiderations for enhanced channel state information reporting duringwireless communications, e.g. during 5G-NR communications.Alternatively, the processor(s) 404 may be configured as a programmablehardware element, such as an FPGA (Field Programmable Gate Array), or asan ASIC (Application Specific Integrated Circuit), or a combinationthereof. In the case of certain RATs, for example Wi-Fi, base station102 may be designed as an access point (AP), in which case network port470 may be implemented to provide access to a wide area network and/orlocal area network(s), e.g. it may include at least one Ethernet port,and radio 430 may be designed to communicate according to the Wi-Fistandard. Base station 102 may operate according to the various methodsand embodiments as disclosed herein for communicating with UE devicesthat codebook subset restriction based on both spatial and frequencyconsiderations for enhanced channel state information reporting duringwireless communications, e.g. during 5G-NR communications, as disclosedherein.

FIG. 5—Exemplary Cellular Communication Circuitry

FIG. 5 illustrates an exemplary simplified block diagram illustrative ofcellular controller 352, according to some embodiments. It is noted thatthe block diagram of the cellular communication circuitry of FIG. 5 isonly one example of a possible cellular communication circuit; othercircuits, such as circuits including or coupled to sufficient antennasfor different RATs to perform uplink activities using separate antennas,or circuits including or coupled to fewer antennas, e.g., that may beshared among multiple RATs, are also possible. According to someembodiments, cellular communication circuitry 352 may be included in acommunication device, such as communication device 106 described above.As noted above, communication device 106 may be a user equipment (UE)device, a mobile device or mobile station, a wireless device or wirelessstation, a desktop computer or computing device, a mobile computingdevice (e.g., a laptop, notebook, or portable computing device), atablet and/or a combination of devices, among other devices.

The cellular communication circuitry 352 may couple (e.g.,communicatively; directly or indirectly) to one or more antennas, suchas antennas 335 a-b and 336 as shown. In some embodiments, cellularcommunication circuitry 352 may include dedicated receive chains(including and/or coupled to (e.g., communicatively; directly orindirectly) dedicated processors and/or radios) for multiple RATs (e.g.,a first receive chain for LTE and a second receive chain for 5G NR). Forexample, as shown in FIG. 5, cellular communication circuitry 352 mayinclude a first modem 510 and a second modem 520. The first modem 510may be configured for communications according to a first RAT, e.g.,such as LTE or LTE-A, and the second modem 520 may be configured forcommunications according to a second RAT, e.g., such as 5G NR.

As shown, the first modem 510 may include one or more processors 512 anda memory 516 in communication with processors 512. Modem 510 may be incommunication with a radio frequency (RF) front end 530. RF front end530 may include circuitry for transmitting and receiving radio signals.For example, RF front end 530 may include receive circuitry (RX) 532 andtransmit circuitry (TX) 534. In some embodiments, receive circuitry 532may be in communication with downlink (DL) front end 550, which mayinclude circuitry for receiving radio signals via antenna 335 a.

Similarly, the second modem 520 may include one or more processors 522and a memory 526 in communication with processors 522. Modem 520 may bein communication with an RF front end 540. RF front end 540 may includecircuitry for transmitting and receiving radio signals. For example, RFfront end 540 may include receive circuitry 542 and transmit circuitry544. In some embodiments, receive circuitry 542 may be in communicationwith DL front end 560, which may include circuitry for receiving radiosignals via antenna 335 b.

In some embodiments, a switch 570 may couple transmit circuitry 534 touplink (UL) front end 572. In addition, switch 570 may couple transmitcircuitry 544 to UL front end 572. UL front end 572 may includecircuitry for transmitting radio signals via antenna 336. Thus, whencellular communication circuitry 352 receives instructions to transmitaccording to the first RAT (e.g., as supported via the first modem 510),switch 570 may be switched to a first state that allows the first modem510 to transmit signals according to the first RAT (e.g., via a transmitchain that includes transmit circuitry 534 and UL front end 572).Similarly, when cellular communication circuitry 352 receivesinstructions to transmit according to the second RAT (e.g., as supportedvia the second modem 520), switch 570 may be switched to a second statethat allows the second modem 520 to transmit signals according to thesecond RAT (e.g., via a transmit chain that includes transmit circuitry544 and UL front end 572).

As described herein, the first modem 510 and/or the second modem 520 mayinclude hardware and software components for implementing any of thevarious features and techniques described herein. The processors 512,522 may be configured to implement part or all of the features describedherein, e.g., by executing program instructions stored on a memorymedium (e.g., a non-transitory computer-readable memory medium).Alternatively (or in addition), processors 512, 522 may be configured asa programmable hardware element, such as an FPGA (Field ProgrammableGate Array), or as an ASIC (Application Specific Integrated Circuit).Alternatively (or in addition) the processors 512, 522, in conjunctionwith one or more of the other components 530, 532, 534, 540, 542, 544,550, 570, 572, 335 and 336 may be configured to implement part or all ofthe features described herein.

In addition, as described herein, processors 512, 522 may include one ormore processing elements. Thus, processors 512, 522 may include one ormore integrated circuits (ICs) that are configured to perform thefunctions of processors 512, 522. In addition, each integrated circuitmay include circuitry (e.g., first circuitry, second circuitry, etc.)configured to perform the functions of processors 512, 522.

In some embodiments, the cellular communication circuitry 352 mayinclude only one transmit/receive chain. For example, the cellularcommunication circuitry 352 may not include the modem 520, the RF frontend 540, the DL front end 560, and/or the antenna 335 b. As anotherexample, the cellular communication circuitry 352 may not include themodem 510, the RF front end 530, the DL front end 550, and/or theantenna 335 a. In some embodiments, the cellular communication circuitry352 may also not include the switch 570, and the RF front end 530 or theRF front end 540 may be in communication, e.g., directly, with the ULfront end 572.

Codebook Subset Restriction (CBSR) and Channel State Information (CSI)Reporting

As previously mentioned, CBSR is used to restrict the precoding matrixcandidates that a UE may consider for CSI reporting. That is, the UE maybe configured such that some precoder candidates are not to beconsidered for CSI reporting, and thus not to be requested from the basestation. Overall, for multi-user multiple-in multiple-pout (MU-MIMO)systems, a base station (e.g. gNB) may force multiple UEs (e.g. two UEs)to report their precoding matrices, or precoding matrix candidates inmutually orthogonal directions. For example, a gNB may request a firstUE to report precoders formed by beams 0, 1, and request a second UE toreport precoders formed by beams 2, 3. In order to reduce the CSIcomputation complexity for the UE, a gNB may remove from consideration,based on uplink measurements, certain unlikely beams, thereby allowingthe UE to not have to test the precoders formed by those beams that wereremoved from consideration. In other words, in order to reducecomputation complexity, based on UL measurements the gNB can restrictthe UE to narrow down the search space, the UE therefore not having toconsider the entire codebook.

In 3GPP new radio (NR, or 5G-NR) systems, two types of codebook, Type Icodebook and Type II codebook, have been standardized for CSI feedbackin support of advanced MIMO operations. The two types of codebook areconstructed from a two-dimensional (2D) digital Fourier transform (DFT)based grid of beams, enabling CSI feedback of beam selection and phaseshift keying (PSK) based co-phase combining between two polarizations.Type II codebook based CSI feedback also reports the wideband andsubband amplitude information of the selected beams, allowing for moreaccurate CSI to be obtained. This, in turn, provides improved precodedMIMO transmissions over the network.

FIG. 6 shows an exemplary diagram illustrating the precoding structureassociated with Type II CSI reporting, according to prior art. The CSImay be reported to the base station (gNB) to indicate which precoding ispreferred by the UE. As mentioned above, there are two types ofcodebooks for CSI reporting, or, worded differently, two types of CSIreporting, Type I and Type II. In Type II reporting, the precodingmatrix is reported for each band, and is represented by a linearcombination of a set of a specified number (L) of DFT vectorsrepresenting each column. As illustrated in FIG. 6, there may be aspecified number (N₃) subbands, with a corresponding precoding matrix Wfor each subband. Each precoding matrix includes two columns, w¹ and w².Each column corresponds to the precoding vector for one layer. For eachlayer, the precoding vector may be further divided into two parts, afirst polarization and second polarization. The L DFT vectors are commonfor all subbands and are used in subband-specific combinations.Specifically, each column vector is a weighted summation of thespecified number (L) of vectors. The weighting (or combination)coefficients for the combination/combined weight are indicated in FIG. 6by c₀, c₁, and c₂. As indicated in the example of FIG. 6, v₀, v₁, and v₂represent three DFT vectors. The UE reports to the gNB, which three DFTvectors are preferred.

FIG. 7 shows an exemplary diagram illustrating the reporting structureused by the UE to report back to the base station (e.g. to the gNB),according to prior art. Each subband has its own corresponding set ofcombination coefficients, and eventually the UE needs to report all thecombination coefficients. When considering the reporting by the UE, theType II overhead is dominated by the subband combination coefficient.According to the information shown in FIG. 7, the total number ofentries is 2L×N₃, there is one (1) bit for amplitude, and there arethree (3) bits for phase. In a worst case scenario, there may be 19subbands, 32 transmit (TX) ports, and a CSI payload size of more than1000 bits. Therefore, it would be beneficial to reduce the Type II CSIoverhead.

FIG. 8 shows an exemplary diagram illustrating CBSR associated with TypeII CSI reporting, according to prior art. FIG. 8 provides an indicationof how CBSR is configured. Overall, a bit sequence is provided to theUE. The bit sequence includes two parts, and each sequence indicates themaximum allowed magnitude for the DFT beams. Accordingly, All O₁O₂ beamgroups are divided into two categories, restricted or unrestricted. Forthe basis in an unrestricted beam group, the wideband amplitude is notrestricted (e.g. it may have 8 different values). For the basis in arestricted beam group, a maximum allowed wideband amplitude isconfigured (e.g. it may have 4 different values). That is, therestriction is on a spatial basis. Four spatial basis groups areselected and the maximum wideband amplitude for each beam in thecorresponding basis group is limited.

As indicated in FIG. 8, there are two antennas in the vertical dimension(number [N₁] of antennas=2) and two antennas in the horizontal direction(number [N₂] of antennas=2), yielding sixteen 16 beam groups (BGs). Thebase station (e.g. gNB) selects four (4) out of the sixteen 16 BGs forconsideration. In the example shown, BG 1, BG 5, BG 8, and BG 10 areselected. Selection of these four beam groups is indicated by the firstbit sequence, B1. For each beam group, the gNB further signals the UE ashort sequence containing eight (8) bits. The eight bits are dividedinto four groups, each group corresponding to one beam in this group.The four groups are shown in FIG. 8 as B₂ ⁽⁰⁾, B₂ ⁽¹⁾, B₂ ⁽²⁾, and B₂⁽³⁾, which can indicate four different maximum amplitude levels. Thereare four beams in each group, and each beam can indicate the maximumallowed power that the UE may consider in reporting CSI. The maximumamplitude may thereby be controlled for spatial beams. Thus, shown inFIG. 8, CBSR restricts beam groups 1, 5, 8, and 10, with each groupconsisting of an N₁N₂ basis, with the maximum wideband amplitudeconfigured for each beam in each restricted beam group.

FIG. 9 shows an exemplary diagram illustrating improved CBSR associatedwith Type II CSI reporting, according to some embodiments. As previouslymentioned, overhead may consume substantial uplink code bandwidth. Insome embodiments, in order to reduce overhead, frequency compression ofthe combination (or weighting) coefficients may be introduced.Therefore, in addition to spatial basis considerations (previouslydescribed), frequency basis may also be considered. If a channel is lessfrequency-selective, neighboring coefficients may exhibit similarity.For example, {c_(i,n) ₃ _(,l)}_(n) ₃ ₌₁ ^(N) ³ are correlated. That is,the combination coefficients across the frequency may have somecorrelation (they may be correlated across the frequency). If thiscorrelation is extracted to enable decorrelation, then the coefficientsmay be presented by a small set of frequency bases, W_(f). Therefore,the overhead may be reduced by compressing the combination coefficient({c_(i,n) ₃ _(,l)}_(n) ₃ ₌₁ ^(N) ³ ) across the frequency dimension.Each coefficient may then be based on M bases, where M represents thecorresponding number of bases and is less than N₃, that is, M<N₃. Thisallows the UE to report a small number of combination coefficients whilealso reporting the frequency basis (or bases) to have the gNBreconstruct the first subband combination coefficients. Coding vectorsmay therefore be presented not only in the spatial dimension but also infrequency dimension. As noted in FIG. 9, w₁ represents the spatial basiscolumn, and w_(f) represents the frequency basis column. Accordingly, anew CBSR may be devised in which the codebook may be restricted on afrequency basis in addition to being restricted on spatial basis.Following decorrelation, wideband amplitude may no longer be applicable.

Pursuant to the above, separate spatial and frequency restrictions maybe implemented for CBSR. Accordingly, the UE may now receive anindication of codebook subset restriction on a spatial basis and also ona frequency basis. In other words, the CBSR may be performed on both aspatial and frequency basis. Thus, the UE may be restricted fromreporting CSI based on a subset of frequency bases per gNBconfiguration, in addition to a spatial basis restriction per the gNBconfiguration. In some embodiments, the maximum allowed amplitude may beseparately configured for a spatial basis and for a frequency basis,yielding a separate maximum allowed amplitude based on spatialconsideration and a separate maximum allowed amplitude based onfrequency consideration. The maximum allowed amplitude may be layerspecific, i.e., each layer may be configured with a different maximumallowed amplitude for different ranks. At least three differentcombinations of spatial/frequency basis consideration may beimplemented. In a first implementation, a UE may be configured withrestricted spatial basis dependent amplitude and unrestricted frequencybasis dependent amplitude. In a second implementation, the UE may beconfigured with restricted frequency basis dependent amplitude andunrestricted spatial basis dependent amplitude. Finally, in a thirdimplementation, the UE may be configured with both restricted spatialbasis dependent amplitude and restricted frequency basis dependentamplitude.

Separate Spatial and Frequency Restrictions

As mentioned above, in some embodiments, both the maximum allowedamplitude for spatial basis and the maximum allowed amplitude forfrequency basis may be configured. This may be implemented in a varietyof different embodiments which may be grouped into three differentalternatives. In a first alternative, the amplitude of each coefficientmay be represented by at most three components, as expressed by theequation c_(i,m,l)=P_(i,l) ⁽¹⁾P_(i,m,l) ⁽²⁾P_(m,l) ⁽³⁾·Ø_(i,m,l), wherethe three components are:

-   -   a spatial basis dependent amplitude (P_(i,l) ⁽¹⁾);    -   a frequency basis dependent amplitude (P_(m,l) ⁽³⁾); and    -   an amplitude dependent on both spatial basis and frequency basis        (P_(i,m,l) ⁽²⁾);        where (P_(i,l) ⁽¹⁾) and (P_(i,l) ⁽¹⁾) shall not exceed the        configured maximum allowed value(s), respectively. In a second        alternative, the amplitude of each coefficient may be        represented by a single component P_(i,m,l), where P_(i,m,l)        shall not exceed the maximum allowed value configured for the        corresponding spatial basis (or bases), and shall also not        exceed the maximum allowed value configured for the        corresponding frequency basis (or bases). In a third        alternative, the amplitude of each coefficient may be        represented by a single component P_(i,m,l), where P_(i,m,l)        shall not exceed the product of the maximum allowed values        configured for the corresponding spatial basis (or bases) and        frequency basis (or bases).

FIG. 10 shows a diagram illustrating one example of separate spatialbasis and frequency basis restrictions, according to some embodiments.In embodiments exemplified in FIG. 10, a 2-bit indication may beprovided to the UE by the gNB for each frequency component. That is, foreach frequency basis (FC), a 2-bit amplitude restriction may beconfigured. When the amplitude is set to zero for a given frequencycomponent, the given frequency component is restricted entirely. Inother words, the given frequency component may not be considered for CSI(or PMI) reporting by the UE. As shown in FIG. 10, for FC 0, theamplitude restriction is 1, for FC 2, the amplitude restriction is ½,and FCs 1 and 3 are entirely restricted from CSI reporting. In thebottom diagram of FIG. 10, the frequency basis restriction is indicatedon the vertical axis while the spatial basis restriction is indicated onthe horizontal axis. Consistent with FIGS. 6 through 9, beam groups 1,5, 8, and 10 are restricted on a spatial basis.

Joint Spatial-Frequency Restriction

FIG. 11 shows a diagram illustrating one example of jointspatial-frequency restriction, according to some embodiments. Asillustrated in FIG. 11, a UE may be restricted from reporting a subsetof combinations of spatial and frequency bases per gNB configuration. Insuch a case the UE may be configured with a subset of spatial basisgroups, with a set of frequency basis restriction configured for eachspatial basis group. When a frequency basis is restricted, it may not beconsidered (by the UE) for CSI reporting with the associated spatialbasis. For each spatial basis group, a maximum allowed amplitude may beconfigured for each basis in the group. That is, a maximum allowedamplitude may be indicated for each combination. For each beam group,the frequency component to be used may also be indicated. For maximumamplitude, the configuration for the beam groups may still be followed.

In the example shown in FIG. 11, for each restricted spatial beam group,a specific frequency basis restriction is configured. On the other hand,for spatial basis groups without restriction, the frequency basis is notrestricted. In contrast to the example shown in FIG. 10, where frequencybases 1 and 3 were restricted completely (regardless of spatial basis),in the example of FIG. 11, spatially unrestricted beam groups 0 and 15are not frequency restricted. However, as indicated by the respectivefrequency basis restriction for each spatially restricted beam group (1,5, 8, and 10), each spatially restricted beam group may also have afrequency basis restriction applied as shown.

In some embodiments, frequency basis restriction and spatial basisrestriction may not be applied simultaneously. That is, restriction maybe either on a spatial basis or a frequency basis, depending on certainparameters. For example, the applicability of spatial/frequencyrestriction may be dependent on the spatial/frequency granularity.Considering the number (N₁, N₂) of transmit ports or antennas, a smallernumber of antennas (e.g. N₁ and N₂ are both either equal to or lowerthan 4) may suggest wider spatial beams and less PMI hypotheses, forwhich a spatial basis restriction may be less efficient, and therefore afrequency basis restriction may be preferred. Thus, in some embodiments,for CBSR, a frequency basis restriction may be provided by gNB to the UEbut not a spatial basis restriction. On the other hand, a larger numberof antennas (e.g. N₁ and N₂ are both either equal to or larger than 8)may suggest narrow spatial beams and more PMI hypotheses, for which eachspatial beam may correspond to a single frequency basis, therefore aspatial basis restriction may be sufficient. Thus, in some embodiments,for CBSR, a spatial basis restriction may be provided by gNB to the UEbut not a frequency basis restriction. Thus, frequency basis restrictionmay be supported for some combination of (N1, N2), and the configurationof frequency basis restriction may be at least partially based on thevalue of (N1, N2).

Configuring the Number of Frequency Bases for Enhanced Type II CSIReporting

Referring again to FIGS. 6 through 9, as previously mentioned, in someembodiments, the frequency basis may be beam specific. For example,frequency basis may be considered for different polarizations and fordifferent spatial beams. FIG. 12 shows a diagram of an exemplaryprecoder structure with frequency compression, according to someembodiments. The equation in FIG. 12 represents the aggregated precodingvector for the lth layer. In the exemplary configuration shown in FIG.12, there are L spatial bases (or beams) per polarization, with L=2 andthe spatial bases (per polarization) denoted by v₀ and v₁, respectively.As shown in FIG. 12, v₀ represents the first spatial beam (or spatialbasis) of the first polarization with corresponding number M₀ frequencybases. The second spatial beam (or spatial basis) v₁ in the firstpolarization may have a smaller corresponding number M₁ of frequencybases. Similarly, v₀ for the second polarization has a correspondingnumber M₂ of frequency bases, and v₁ for the second polarization has acorresponding number M₃ of frequency bases. That is, M₀ represents thenumber of frequency bases corresponding to v₀ in the first polarization,M₁ represents the number of frequency bases corresponding to v₁ in thefirst polarization, M₂ represents the number of frequency basescorresponding to v₀ in the second polarization, and M₃ represents thenumber of frequency bases corresponding to v₁ in the secondpolarization. Upon determining the respective values (of) M₀, M₁, M₂ andM₃, the value (of) M may obtained, which represents (corresponds to) the(horizontal) dimension of the W₂ matrix. Accordingly, M (or the value ofM) also represents the number of overall frequency bases (or verticaldimension) of the W_(f) matrix. N₃ (or the value of N₃) represents thenumber of frequency units (e.g. the number of subbands).

For each ith spatial basis, the corresponding combination coefficient isa linear combination of the corresponding number M_(i) of frequencybases. The value (of) M_(i) maybe selected by the UE and reported inCSI, or it may be configured in the UE by the gNB via higher-layer (e.g.RRC) signaling. In some embodiments, referred to as explicitconfiguration, the gNB may configure the value in the UE via dedicatedradio resource control (RRC) signaling. For example, the UE may obtainthe value of M_(i) explicitly from the base station via dedicatedhigher-layer (e.g. RRC) signaling. In some embodiments, referred to asimplicit configuration, the value may be derived by the UE from someother RRC parameters based on specified, predefined rules.

In a first implementation, the value (of) M_(i) may be a function of thenumber of ports in both dimensions (vertical and horizontal). That is,the value (of) M_(i) may be a function of (N₁, N₂). A large number of N₁and N₂ (again, equal to or greater than 8, for example) may result in anarrower spatial beam, and a small Mi value may therefore be sufficient.

In a second implementation, the frequency dimension may be considered.Here the UE may be required to report a large number of subbands. Thevalue (of) M_(i) may be a function of N₃. A large N₃ value may result inmore resolvable paths, therefore a large M_(i) value may be preferable.E.g., M_(i)=f₂(N₃).

In a third implementation, both spatial and frequency considerations maybe taken into account. In this case the value (of) M_(i) may be afunction of (N₁, N₂, N₃), and the spatial-temporal granularity may bejointly considered. E.g., M_(i)=f₃(max(N₁, N₂), N₃).

Configuring PMI Frequency Compression Units for Enhanced NR Type II CSI

Referring again to FIG. 9, consideration may be given to determining thelength of the frequency basis. In practical terms this leads todetermining how to choose the dimension of the W_(f) matrix. It shouldbe noted that there is a clear relationship between the frequency andthe time domain (Fourier Transform), which makes it possible to use aFast Fourier Transform (FFT). For example if the UE is required toreport CSI for a specified number (e.g. 5) of subbands, then the columnof W_(f) may have a corresponding same number (in this case 5) entries.The value for each subband may be obtained. In proposed systems, the no.of resource blocks (RBs) may range from 1 to 275 (as an example of thewider range). Thus, FFT may be supported for this range. Arelationship/link may be established between the number of CSI frequencyunits and the FFT size for the dimension of W_(f).

The frequency basis in W_(f) may be a subset of DFT vectors. Thedimension of the frequency basis may thus equal to the number of CSIfrequency units (e.g., the number of subbands as indicated in the CSIreporting band). The number of subbands may be any integer in aspecified range, for example in the range of 1 to 19, according tocurrent 3GPP specifications. For finer PMI frequency units, thedimension of the frequency basis may vary in a much wider range, e.g.from 1 to hundreds. As mentioned above, the frequency compression may beimplemented through FFT. In order to facilitate the implementation, thedimension of the frequency basis (e.g., FFT size) may be carefullyselected.

Pursuant to the above, a new dimension labeled N″₃ may be introduced.N′₃ may be specified to be less than the FFT size, which is thedimension of each column of the W_(f) matrix as denoted by N″₃. Thedimension of frequency basis may thus be defined by N″₃=2^(i)3^(j)5^(k),for FFT implementation. The values of i, j, k may selected such that N″₃is the smallest integer larger than N′₃, where N′₃ is the maximum numberof the PMI FD compression units in the given bandwidth part (BWP) or inthe given component carrier (CC). N₃, then, is the number of the PMI FDcompression units to be reported, and may be less than N′₃. E.g., thegNB may disable some subbands by setting the corresponding bits to ‘0’sin the CSI reporting band. Therefore, the following inequality may beobserved: N″₃≥N′₃≥N₃.

FIG. 13 shows a diagram illustrating an example of PMI frequencycompression unit configuration, according to some embodiments. As shownin FIG. 12, the BWP contains N′₃=7 (seven) subbands. The value in theCSI reporting band=1011011, that is, the UE is requested to report CSIon subbands 0, 2, 3, 5, and 6, which means that N₃=5. The frequencybasis dimension is then N″₃=8. FIG. 14 shows a table of exemplarycorresponding values of i, j, k, and N″₃ for all the N₃ values from 1 to19.

It is well understood that the use of personally identifiableinformation should follow privacy policies and practices that aregenerally recognized as meeting or exceeding industry or governmentalrequirements for maintaining the privacy of users. In particular,personally identifiable information data should be managed and handledso as to minimize risks of unintentional or unauthorized access or use,and the nature of authorized use should be clearly indicated to users.

Embodiments of the present invention may be realized in any of variousforms. For example, in some embodiments, the present invention may berealized as a computer-implemented method, a computer-readable memorymedium, or a computer system. In other embodiments, the presentinvention may be realized using one or more custom-designed hardwaredevices such as ASICs. In other embodiments, the present invention maybe realized using one or more programmable hardware elements such asFPGAs.

In some embodiments, a non-transitory computer-readable memory medium(e.g., a non-transitory memory element) may be configured so that itstores program instructions and/or data, where the program instructions,if executed by a computer system, cause the computer system to perform amethod, e.g., any of a method embodiments described herein, or, anycombination of the method embodiments described herein, or, any subsetof any of the method embodiments described herein, or, any combinationof such subsets.

In some embodiments, a device (e.g., a UE) may be configured to includea processor (or a set of processors) and a memory medium (or memoryelement), where the memory medium stores program instructions, where theprocessor is configured to read and execute the program instructionsfrom the memory medium, where the program instructions are executable toimplement any of the various method embodiments described herein (or,any combination of the method embodiments described herein, or, anysubset of any of the method embodiments described herein, or, anycombination of such subsets). The device may be realized in any ofvarious forms.

Although the embodiments above have been described in considerabledetail, numerous variations and modifications will become apparent tothose skilled in the art once the above disclosure is fully appreciated.It is intended that the following claims be interpreted to embrace allsuch variations and modifications.

The invention claimed is:
 1. An apparatus comprising: a processor configured to cause a device to: obtain a value, M, for a dimension of a basis of an enhanced channel state information (CSI) feedback, wherein the CSI feedback is for a specific number, S, of frequency subbands and includes information corresponding to a coefficient matrix having a dimension of 2L by M, wherein L is a number of beams associated with the CSI feedback, wherein M is a result of a compression of a number, N, of frequency units, wherein N is based on S, and wherein M is less than S; and wirelessly transmit, to a base station, the enhanced CSI feedback.
 2. The apparatus of claim 1, wherein the processor is configured to further cause the device to select the value of M.
 3. The apparatus of claim 1, wherein the processor is configured to further cause the device to transmit the value M in the enhanced CSI feedback.
 4. The apparatus of claim 1, wherein the processor is configured to further cause the device to obtain the value M explicitly from the base station via dedicated higher-layer signaling.
 5. The apparatus of claim 1, wherein the processor is configured to further cause the device to obtain the value M by deriving the value M from other parameters based on higher-layer signaling from the base station and further based on specified, predefined rules.
 6. The apparatus of claim 1, wherein the processor is configured to further cause the device to determine the value M in part based on one or more of: a number N₁ of transmitting antennas in the vertical dimension; or a number N₂ of transmitting antennas in the horizontal dimension; wherein the beams associated with the CSI feedback include a plurality of beams divided into groups, wherein each group has an N₁×N₂ dimension.
 7. The apparatus of claim 1, wherein the processor is configured to further cause the device to: obtain a respective value M for each spatial basis of a plurality of spatial bases of the enhanced channel CSI feedback.
 8. A device comprising: radio circuit configured to enable wireless communications of the device; and a processor communicatively coupled to the radio circuit and configured to cause the device to: obtain a value, M, for a dimension of a basis of an enhanced channel state information (CSI) feedback, wherein the CSI feedback is for a specific number, S, of frequency subbands and includes information corresponding to a coefficient matrix having a dimension of 2L by M, wherein L is a number of beams associated with the CSI feedback, wherein M is a result of a compression of a number, N, of frequency units, wherein N is based on S, and wherein M is less than S; and wirelessly transmit, to a base station, the enhanced CSI feedback.
 9. The device of claim 8, wherein the processor is configured to further cause the device to select the value of M.
 10. The device of claim 8, wherein the processor is configured to further cause the device to transmit the value M in the enhanced CSI feedback.
 11. The device of claim 8, wherein the processor is configured to further cause the device to obtain the value M explicitly from the base station via dedicated higher-layer signaling.
 12. The device of claim 8, wherein the processor is configured to further cause the device to obtain the value M by deriving the value M from other parameters based on higher-layer signaling from the base station and further based on specified, predefined rules.
 13. The device of claim 8, wherein the processor is configured to further cause the device to determine the value M in part based on one or more of: a number N₁ of transmitting antennas in the vertical dimension; or a number N₂ of transmitting antennas in the horizontal dimension; wherein the beams associated with the CSI feedback include a plurality of beams divided into groups, wherein each group has an N₁×N₂ dimension.
 14. The device of claim 8, wherein the processor is configured to further cause the device to: obtain a respective value M for each spatial basis of a plurality of spatial bases of the enhanced channel CSI feedback.
 15. A non-transitory memory element storing programming instructions executable by a processor to: obtain a value, M, for a dimension of a basis of an enhanced channel state information (CSI) feedback, wherein the CSI feedback is for a specific number, S, of frequency subbands and includes information corresponding to a coefficient matrix having a dimension of 2L by M, wherein L is a number of beams associated with the CSI feedback, wherein M is a result of a compression of a number, N, of frequency units, wherein N is based on S, and wherein M is less than S; and wirelessly transmit, to a base station, the enhanced CSI feedback.
 16. The non-transitory memory element of claim 15, wherein the processor is configured to further cause the device to transmit the value M in the enhanced CSI feedback.
 17. The non-transitory memory element of claim 15, wherein the processor is configured to further cause the device to obtain the value M explicitly from the base station via dedicated higher-layer signaling.
 18. The non-transitory memory element of claim 15, wherein the processor is configured to further cause the device to obtain the value M by deriving the value M from other parameters based on higher-layer signaling from the base station and further based on specified, predefined rules.
 19. The non-transitory memory element of claim 15, wherein the processor is configured to further cause the device to determine the value M in part based on one or more of: a number N₁ of transmitting antennas in the vertical dimension; or a number N₂ of transmitting antennas in the horizontal dimension; wherein the beams associated with the CSI feedback include a plurality of beams divided into groups, wherein each group has an N₁ ×N₂ dimension.
 20. The non-transitory memory element of claim 15, wherein the processor is configured to further cause the device to: obtain a respective value M for each spatial basis of a plurality of spatial bases of the enhanced channel CSI feedback. 